The vasovagal response during confrontation with blood-injury-injection stimuli: The role of perceived control

Highlights

• We examined the effect of perceived control on the vasovagal response.

• Perceived control led to less vasovagal symptoms and lower anxiety.

• Participants who were fearful of blood benefitted more from perceived control.

Abstract

The vasovagal response (VVR) is a common medical problem, complicating and deterring people from various procedures. It is an unusual stress response given the widespread decreases in physiological activity. Nevertheless, VVR involves processes similar to those observed during episodes of strong emotions and pain. We hypothesized that heightened perceived control would reduce symptoms of VVR. Eighty-two young adults were randomly assigned to perceived control or no perceived control conditions during exposure to a stimulus video of a mitral valve surgery, known to trigger VVR in non-medical personnel. Perceived control was manipulated by allowing some participants to specify a break time, though all received equivalent breaks. Outcomes included subjective symptoms of VVR, anxiety, blood pressure, heart rate, and other measures derived from impedance cardiography. Compared to participants with perceived control, participants with no perceived control reported significantly more vasovagal symptoms and anxiety, and experienced lower stroke volume, cardiac output, and diastolic blood pressure. Participants who were more fearful of blood were more likely to benefit from perceived control in several measures. Perceived control appears to reduce vasovagal symptoms. Results are discussed in terms of cognition and emotion in VVR.

Introduction

Over one million people are evaluated for syncope in the United States annually (Fenton, Hammill, Rea, Low, & Shen, 2000) accounting for 1% of emergency department visits (Blanc et al., 2002, Brignole et al., 2003) and 3.6% of hospital admissions (Morichetti & Astorino, 1998). Many more cases do not come to the attention of medical personnel. Of the various possible causes of syncope, the vasovagal response (VVR) is the most common (Manolis, Linzer, Salem, & Estes, 1990). VVR, with or without syncope, also causes significant distress and can deter people from routine medical activities such as immunization, dental care, and blood donation (Enkling et al., 2006, France et al., 2004, Marks, 1988, Nir et al., 2003, Page, 1996).

The vasovagal process is complex and can be triggered by different physical and psychological stimuli such as a hot environment, prolonged standing, hemorrhage, and psychological stress. For many years, theorists have emphasized low control or submission to a threat as key determinants of the likelihood of a stress-related VVR (Engel, 1962, Engel, 1978, Sledge, 1978). While all stress responses are related to at least some lack of perceived control over the environment – life problems with easy and available solutions are unlikely to cause a stress response (Lazarus and Folkman, 1984, Sanderson et al., 1989) – the emphasis has been especially strong in models of VVR.

Graham, Kabler, and Lunsford (1961) argued that vasovagal syncope is the result of parasympathetic rebound related to a state of relief that follows a period of strong uncontrollable stress. Although his ideas changed with time, Engel consistently emphasized the idea of an adaptive surrender to uncontrollable stress (Engel, 1978, Engel and Romano, 1947). Page (1994) suggested that vasovagal syncope results from a dual process in which fear is accompanied by a sense of disgust perhaps due to the possibility of unavoidable body envelope violation. More recent models have suggested that stress-related vasovagal syncope develops as a physiological preparation for unavoidable injury, perhaps as a means of deterring aggression (Bracha, 2004) or stemming blood loss (Barlow, 1988, Diehl, 2005, Ditto et al., 2012a, Ditto et al., 2012b). Relatedly, it is interesting to note that VVR is the most common in medical settings in which people are required to passively endure unpleasant procedures (Enkling et al., 2006, France et al., 2004, Nir et al., 2003, Page, 1996) and is especially common among individuals with pre-existing fears of blood, injury, and injections (Marks, 1988).

Given this focus on lack of control, it is reasonable to predict that enhancing an individual's sense of control over stress would reduce VVR. Indeed, it has been argued that the fear of losing control may be central to the progression of VVR (Ritz, Meuret, & Ayala, 2010). Fainting and related vasovagal symptoms are often a primary complaint and a central treatment focus in cognitive-behavioral therapies for Blood-Injury-Injection Phobia (Hellström and Fellenius, 1996, Öst et al., 1991). In a recent review, Ritz et al. (2010) discussed successful treatment studies of Blood-Injury-Injection-Phobia which did not focus on treatment of fainting. Patients who had improved at follow-up also reported no longer using a technique designed to manage fainting or other symptoms of VVR, (i.e., applied tension). The authors point to perceived control as a possible explanation (Ritz et al., 2010).

The primary goal of this study was to examine the effects of an experimental manipulation believed to enhance participants’ sense of perceived control on their responses to a “prototypical” VVR-inducing stimulus, i.e., passively watching a video of a surgical procedure. It was predicted that an increased sense of perceived control would reduce physiological correlates of VVR and vasovagal symptoms. A secondary aim of the study was to examine the relative effects of individual differences in fear of blood and fear of needles on VVR, and their interaction with perceived control. In the previous study (Gilchrist & Ditto, 2012), we found that a video of blood withdrawal elicited stronger VVR than a virtually identical video of an intravenous injection. Thus, in the present study, it was predicted that participants who were especially fearful of blood loss would be most likely to display VVR and to benefit from enhanced perceived control.